The present invention relates to fire-resistant containers; more particularly, to fire-resistant safes; and most particularly, to a safe container which is both fire-resistant and water-resistant.
Containers for temporarily protecting their contents from damage from external heat sources such as fire are well known. Such containers are said in the art to be xe2x80x9cfire-resistantxe2x80x9d and typically are rated for integrity over a specific exposure temperature and/or time. Lockable fire-resistant containers are known as fire-resistant xe2x80x9csafesxe2x80x9d and are widely used for storage of documents or other valuables which may be damaged or destroyed by exposure to high temperatures. For example, various models of such fire-resistant safes are available from Sentry Group, Rochester, N.Y. 14625 USA.
A typical top-opening fire-resistant safe has top and bottom elements which are hinged and detachably latched together to form a storage cavity between the elements. Each element is initially hollow, having inner and outer shells which may be conveniently formed as by blow-molding or other known forming means. The interior of each element between the shells is filled with a non-combustible, fire-proof thermally-insulating material such as Portland cement, which typically is heavily hydrated. The shells are formed of polymeric resin having a melting point higher than the boiling point of water such that the hydration prevents the shells, and especially the outer shells, from melting or igniting for an extended period of time. See, for example, fire-resistant safes as disclosed in U.S. Pat. No. 5,295,447 issued Mar. 22, 1994 to Robbins et al., the relevant disclosure of which is hereby incorporated by reference, as are the various other US Patents incorporated by reference therein.
A common problem encountered in use of prior art fire-resistant safes is that they may be inundated with water from fire hoses during the fighting of a fire. Water may leak into the interior of a safe through the hinges and jamb and may ruin contents which have been otherwise preserved from damage by the fire. Such safes have no specific barrier to water entry, such as a resilient sealing gasket at the interface between the top and bottom elements. See, for example, the relevant disclosure of U.S. Pat. No. 4,541,545 issued Sep. 17, 1985 to Beattie et al.
One approach to making a fire-resistant safe also water-resistant is found in the construction of known xe2x80x9cdiving boxesxe2x80x9d intended for underwater use wherein a jamb and corresponding gasket are provided around the entire periphery of the mating portions of the top and bottom elements. An external hinge connects the top and bottom elements, and the cover is locked by one or more over-center latches such that the gasket is highly compressed.
A problem arises is adapting this construction to fire- and water-resistant containers wherein the outer shell is progressively destroyed by fire. Because the gasket is so compressed, when either the hinge or the latches are first burned away, the resilience of the gasket can cause the safe to spring open enough to destroy the water seal. Further, if the axis of the hinge lies in or near the plane containing the sealing surfaces, the region including the surfaces nearest the hinge will become engaged the earliest during closing of the safe and the gasket may ultimately be more compressed in that region than in the region of the latch. Thus, when the hinges are burned away the safe may spring open even though the latch is still intact, exposing the contents to fire and/or water.
What is needed is a fire- and water-resistant container having a gasket at the interface between a top and a bottom element, the elements being hinged and latched together, wherein the gasket is lightly and evenly loaded over its entire length such that a fire- and water-resistant seal between the elements is maintained when the hinges and/or latch are destroyed.
It is the primary object of the invention to provide an improved fire-resistant and water-resistant safe for storage of documents or other valuables.
The invention is directed to a fire-resistant container which has a full gasket at the interface between highly-insulated top and bottom elements thereof which are rotated closed to a storage space therein. The elements are each formed with a labyrinthine edge surrounding the open side, the elements meeting matably along the edges. One of the edges, preferably the edge of the top element, is provided with a smooth, soft gasket disposed in a groove in the labyrinth which forms a seal against a corresponding rib in the opposing edge. The elements are joined along a first common side, preferably the back side, by at least one hinge, the rotational axis of which is positioned in space relative to the gasket and rib such that, in closing of the container, the gasket engages the rib at all points substantially simultaneously. The elements are secured along a second common side, preferably the front side, by over-center latching means such that when the container is fully closed the rib exerts a small and substantially uniform force against the gasket. Upon being exposed to fire, the hinges and/or the latch may be destroyed without causing the seal between the gasket and the rib to be broken, thus maintaining the fire- and water-resistance of the container. In a top-opening embodiment, the weight of the top element, when freed from gravitational restraint of the hinges and latch, further compresses the gasket onto the rib, enhancing the seal. In a further preferred embodiment, the gasket material is selected to be able to melt in place while the outer shells are being thermally destroyed, thus forming a viscous seal to enhance the integrity of the container. Preferably, the gasket material emits relatively small amounts of soot upon melting, and the seal prevents any soot generated from the exposed outer surfaces of the gasket from entering the container and damaging the contents.